Problem: What do the following two equations represent? $x+5y = -3$ $-x-5y = 3$
Explanation: Putting the first equation in $y = mx + b$ form gives: $x+5y = -3$ $5y = -x-3$ $y = -\dfrac{1}{5}x - \dfrac{3}{5}$ Putting the second equation in $y = mx + b$ form gives: $-x-5y = 3$ $-5y = x+3$ $y = -\dfrac{1}{5}x - \dfrac{3}{5}$ The above equations turn into the same equation, so they represent equal lines.